Summary: 1
A two-step volunteer's dilemma
Marco Archetti1,2
1
Department of Organismic and Evolutionary Biology, Harvard University
2
Faculty of Business and Economics, University of Basel
E-mail: marco.archetti@unibas.ch
Note
Alarm calls (Clutton-Brock 1999, Searcy & Nowicki 2005) are one of the best examples
of public goods in biology. Unlike other commonly cited examples, such as natural
resources (Hardin 1968) and extracellular enzymes in microbes (Crespi 2001), alarm calls
are completely non-rivalrous (consumption does not reduce availability to others) and
non-excludable (nobody can be excluded from consumption) and are therefore pure
public goods (Samuelson 1954).
If all individuals in a group detect the predator with certainty, alarm calls can be
modelled by the volunteer's dilemma ("VD": Diekmann 1985), an N-person game in
which a public good is produced if and only if at least one player volunteers to pay a cost
c; if the public good is produced all players have a benefit b (>c). A collective action
problem arises: a volunteer benefits from his action if nobody else volunteers, but the cost